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  • #61
    Re: Open and Wide

    Originally posted by jclin4 View Post
    Oh, and I did get my hands dirty with woodworking, just not speakers, this Spring. I made an end table to match the speakers from spare stock:

    [ATTACH=CONFIG]47468[/ATTACH][ATTACH=CONFIG]47467[/ATTACH]
    I get a message saying that there are errors in the files when I try to open them full size (latest Firefox browser).

    dlr
    WinPCD - Windows .NET Passive Crossover Designer

    Dave's Speaker Pages

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    • #62
      Re: Open and Wide

      Interesting, but not sure how to resolve. I can see the images fine in IE9 and Safari browsers, but I did have a problem uploading them.

      After the initial upload, I noticed that one of them needed to be rotated. I deleted and then tried to re-upload the corrected image. The forum software kept reporting an error in uploading (without being more specific). I renamed the file and tried again...samething. So I uploaded the image as is.

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      • #63
        Re: Open and Wide

        Originally posted by dlr View Post
        I get a message saying that there are errors in the files when I try to open them full size (latest Firefox browser).

        dlr
        Works fine here in the latest FF.
        "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche

        http://www.diy-ny.com/

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        • #64
          Re: Open and Wide

          I wish that I had your patience!

          Those not only look great, I'll bet they sound great also, with the very smooth off-axis response.
          This type of design is going into my "one day sometime" project list.

          I think I hear a difference - wow, it's amazing!" Ethan Winer: audio myths
          "As God is my witness I'll never be without a good pair of speakers!" Scarlett O'Hara

          High value, high quality RS150/TB28-537SH bookshelf - TARGAS NLA!
          SB13/Vifa BC25SC06 MTM DCR Galeons-SB13-MTM
          My Voxel min sub Yet-another-Voxel-build

          Tangband W6-sub

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          • #65
            Re: Open and Wide

            Originally posted by jclin4 View Post
            I also kept tweaking the XO throughout the Summer and consider them complete. I've kept the XO boards external, so decided to pretty them up a bit. They are mounted on 1/4" frosted acrylic sheet which are themselves mounted on solid cherry using display risers:

            [ATTACH=CONFIG]40414[/ATTACH]
            Absolutely gorgeous speakers. Great work!

            I was wondering where you got the acrylic sheet, and whether it is difficult to work with/cut/drill, etc.

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            • #66
              Re: Open and Wide

              Originally posted by 50 watt head View Post
              Absolutely gorgeous speakers. Great work!

              I was wondering where you got the acrylic sheet, and whether it is difficult to work with/cut/drill, etc.
              Thanks! The frosted acrylic sheets were purchased on eBay. Vendors are selling scrap pieces which I think are called "drops" at reasonable prices. I just kept my eyes open for particular sizes that met my needs.

              The acrylic was not hard to cut. I used my circular saw and it was just like cutting MDF. The holes were drilled using my handheld with regular bits. Most of the holes drilled cleanly, but a few had small cracks which were not that visible. I didn't drill enough to determine what technique would cause the difference.

              The only other thing to think about is keeping the soldering iron tip away from the acrylic.

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              • #67
                Re: Open and Wide

                Originally posted by jclin4 View Post
                The acrylic was not hard to cut. I used my circular saw and it was just like cutting MDF. The holes were drilled using my handheld with regular bits. Most of the holes drilled cleanly, but a few had small cracks which were not that visible. I didn't drill enough to determine what technique would cause the difference.

                The only other thing to think about is keeping the soldering iron tip away from the acrylic.
                Very helpful -- thanks!

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                • #68
                  Great Looking Speakers!

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                  • #69
                    Thanks! It was several projects ago when I built these with passive crossovers. Now these are back as my main speakers with active crossovers. More info on the new XO:

                    http://techtalk.parts-express.com/fo...metal-shavings

                    The back of these speakers are not so pretty, but let me share what is going on back there:

                    Click image for larger version

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                    The rear of the midrange is covered with Denim stuffing and I have laid down some egg crate padding on the horizontal surface of the woofer cab. This produced a very noticeable improvement subjectively. I tried to measure to see if there was any difference, but none showed up in my initial measurements. Then it dawned on me that I should remove any gating so that results of reflections show up. Sure enough it did (this is with 1/3 smoothing in order to more clearly see the changes - black is without and red with the treatment):

                    Click image for larger version

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                    Anyway, thought this might be interesting.

                    Cheers,
                    - John

                    Attached Files

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                    • #70

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                      • #71
                        Rather than have all that "stuffing" on the back, do it the way Dahlquist did it on the DQ-10 for the midrange. Put a single piece of 1/2" wool felt (square will do) large enough to totally cover and "seal" the midrange unit on the rear. It won't have internal resonances (much anyway), but should damp the majority of the rear wave.

                        dlr
                        WinPCD - Windows .NET Passive Crossover Designer

                        Dave's Speaker Pages

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                        • #72
                          Double post

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                          • #73
                            Hey Dave, thanks for that suggestion. I think I was able to find a pic of what you described. It should be cleaner and more effective:

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                            • #74
                              I think the damping behind to midbass driver in the DQ10s gives more of a carliod response. I really recommend moving the damping material further away from the back of the driver to allow a few inches of air space behind the driver. I have done this several times and the image in the midrange has more depth and the sound does not seem stuck to the speaker location.

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                              • #75
                                Originally posted by fdieck View Post
                                I think the damping behind to midbass driver in the DQ10s gives more of a carliod response. I really recommend moving the damping material further away from the back of the driver to allow a few inches of air space behind the driver. I have done this several times and the image in the midrange has more depth and the sound does not seem stuck to the speaker location.
                                To be cardioid there would need to be some delay of the rear wave. I doubt that a relatively thin piece of felt can provide any significant delay. The felt is primarily damping of a dipole and the range above the dipole region. It will also only be dipole in the region below the step area of the baffle on which the midrange is mounted. On a wide, open baffle that's fairly low in frequency. The dimension of the baffle used here probably places the dipole region well below the range of the midrange driver, so without damping I suspect that it's primarily some randomized interference pattern as measured from the front, a degraded dipole if you will. Damping the back will greatly reduce interaction of the rear wave with the front and will change the in-room perceived response depending on the placement of the system from reflection side and read walls.

                                Experimenting with placement is still a good idea, though but part of the benefit of close positioning would be reduction in any resonances that midranges often suffer due to the thickness of the baffle. The gap between the rear ouput of the midrange and the baffle cutout can create a volume area that may be resonant, just like a port is with moving mass. I've experimented with small midranges and found that damping this area can help. The way Dahlquist positioned the felt is how I would start.

                                dlr
                                WinPCD - Windows .NET Passive Crossover Designer

                                Dave's Speaker Pages

                                Comment

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